/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */#ifndef GFX_MATH_TABLE_H#define GFX_MATH_TABLE_H#include "gfxFont.h"
struct Coverage;
struct GlyphAssembly;
struct MATHTableHeader;
struct MathConstants;
struct MathGlyphConstruction;
struct MathGlyphInfo;
struct MathVariants;
/**
* Used by |gfxFontEntry| to represent the MATH table of an OpenType font.
* Each |gfxFontEntry| owns at most one |gfxMathTable| instance.
*/class gfxMathTable
{
public:
/**
* @param aMathTable The MATH table from the OpenType font
*
* The gfxMathTable object takes over ownership of the blob references
* that are passed in, and will hb_blob_destroy() them when finished;
* the caller should -not- destroy this reference.
*/explicit gfxMathTable(hb_blob_t* aMathTable);
/**
* Releases our reference to the MATH table and cleans up everything else.
*/ ~gfxMathTable();
/**
* Returns the value of the specified constant from the MATH table.
*/int32_t GetMathConstant(gfxFontEntry::MathConstant aConstant);
/**
* If the MATH table contains an italic correction for that glyph, this
* function gets the value and returns true. Otherwise it returns false.
*/bool GetMathItalicsCorrection(uint32_t aGlyphID, int16_t* aItalicCorrection);
/**
* @param aGlyphID glyph index of the character we want to stretch
* @param aVertical direction of the stretching (vertical/horizontal)
* @param aSize the desired size variant
*
* Returns the glyph index of the desired size variant or 0 if there is not
* any such size variant.
*/uint32_t GetMathVariantsSize(uint32_t aGlyphID, bool aVertical,
uint16_t aSize);
/**
* @param aGlyphID glyph index of the character we want to stretch
* @param aVertical direction of the stretching (vertical/horizontal)
* @param aGlyphs pre-allocated buffer of 4 elements where the glyph
* indexes (or 0 for absent parts) will be stored. The parts are stored in
* the order expected by the nsMathMLChar: Top (or Left), Middle, Bottom
* (or Right), Glue.
*
* Tries to fill-in aGlyphs with the relevant glyph indexes and returns
* whether the operation was successful. The function returns false if
* there is not any assembly for the character we want to stretch or if
* the format is not supported by the nsMathMLChar code.
*
*/bool GetMathVariantsParts(uint32_t aGlyphID, bool aVertical,
uint32_t aGlyphs[4]);
protected:
friendclass gfxFontEntry;
// This allows gfxFontEntry to verify the validity of the main headers// before starting to use the MATH table.bool HasValidHeaders();
private:
// HarfBuzz blob where the MATH table is stored. hb_blob_t* mMathTable;
// Cached values for the latest (mGlyphID, mVertical) pair that has been// accessed and the corresponding glyph construction. These are verified// by SelectGlyphConstruction and updated if necessary.// mGlyphConstruction will be set to nullptr if no construction is defined// for the glyph. If non-null, its mGlyphAssembly and mVariantCount fields// may be safely read, but no further validation will have been done.const MathGlyphConstruction* mGlyphConstruction;
uint32_t mGlyphID;
bool mVertical;
void SelectGlyphConstruction(uint32_t aGlyphID, bool aVertical);
// Access to some structures of the MATH table.// These accessors just return a pointer, but do NOT themselves check the// validity of anything. Until we've checked that HasValidHeaders (which// does validate them) returns true, they might return pointers that cannot// even safely be dereferenced. GetGlyphAssembly may return nullptr if the// given glyph has no assembly defined.const MATHTableHeader* GetMATHTableHeader();
const MathConstants* GetMathConstants();
const MathGlyphInfo* GetMathGlyphInfo();
const MathVariants* GetMathVariants();
const GlyphAssembly* GetGlyphAssembly(uint32_t aGlyphID, bool aVertical);
// Verify whether a structure or an offset belongs to the math data and can// be read safely.bool ValidStructure(constchar* aStructStart, uint16_t aStructSize);
bool ValidOffset(constchar* aOffsetStart, uint16_t aOffset);
// Get the coverage index of a glyph index from an Open Type coverage table// or -1 if the glyph index is not found.int32_t GetCoverageIndex(const Coverage* aCoverage, uint32_t aGlyph);
};
#endif